chore(lint): Added license headers to most TypeScript files

Relates to #9380

modules/@angular/common/test/pipes/async_pipe_spec.ts

@@ -1,3 +1,11 @@
+/**
+ * @license
+ * Copyright Google Inc. All Rights Reserved.
+ *
+ * Use of this source code is governed by an MIT-style license that can be
+ * found in the LICENSE file at https://angular.io/license
+ */
+
 import {ddescribe, describe, it, iit, xit, expect, beforeEach, afterEach, inject,} from '@angular/core/testing/testing_internal';
 import {AsyncTestCompleter} from '@angular/core/testing/testing_internal';
 import {SpyChangeDetectorRef} from '../spies';